[POC] use serviceWorker from create-react-app (#1286)

* Service worker with toast notifications

* Update CSP to allow fetches from now.sh

* Fixed clearing timers

* rounded icon for pwa (#1301)

* rounded icon for pwa

* cirle pwa app icon

* fix fonts caching

* fix app

* fix css import

* Updated csp tp inlcude worker-src: self

* add worker CSP rule

* use square icon

Co-authored-by: Timur Khazamov <t1mmaas@skbkontur.ru>
Co-authored-by: Faustino Kialungila <Faustino.kialungila@gmail.com>
Co-authored-by: kbariotis <konmpar@gmail.com>

src/components/App.tsx

@@ -2652,4 +2652,3 @@ if (
 }
 
 export default App;
-// -----------------------------------------------------------------------------